GFS2: Fix type mapping for demote_rq interface

Mostly the glock operations follow the type of the glock. The
one exception is the transaction glock, so we need to check for
that directly.
Reported-by: NDr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glops.c

@@ -452,7 +452,6 @@ const struct gfs2_glock_operations *gfs2_glops_list[] = {
 	[LM_TYPE_META] = &gfs2_meta_glops,
 	[LM_TYPE_INODE] = &gfs2_inode_glops,
 	[LM_TYPE_RGRP] = &gfs2_rgrp_glops,
-	[LM_TYPE_NONDISK] = &gfs2_trans_glops,
 	[LM_TYPE_IOPEN] = &gfs2_iopen_glops,
 	[LM_TYPE_FLOCK] = &gfs2_flock_glops,
 	[LM_TYPE_NONDISK] = &gfs2_nondisk_glops,

fs/gfs2/sys.c

@@ -230,7 +230,10 @@ static ssize_t demote_rq_store(struct gfs2_sbd *sdp, const char *buf, size_t len
 
 	if (gltype > LM_TYPE_JOURNAL)
 		return -EINVAL;
-	glops = gfs2_glops_list[gltype];
+	if (gltype == LM_TYPE_NONDISK && glnum == GFS2_TRANS_LOCK)
+		glops = &gfs2_trans_glops;
+	else
+		glops = gfs2_glops_list[gltype];
 	if (glops == NULL)
 		return -EINVAL;
 	if (!test_and_set_bit(SDF_DEMOTE, &sdp->sd_flags))